The present invention concerns an improved precompression pump particularly intended for spraying or dispensing a fluid, e.g. such as a perfume, a cosmetic or a pharmaceutical. A pump of this kind for a liquid or a semi-liquid is usually operated by a finger.
One specific type of manual precompression pump is described in document FR-2 403 465. That type of pump includes a cylindrical pump housing containing a slidable annular plunger controlled by a push rod which slides in said plunger and includes an outlet channel leading to the pump housing via a side opening, the plunger including a substantially axial annular lip that interacts with the push rod to block or clear said side opening, the push rod being connected to the plunger by a first resilient member which pushes the plunger back into a position in which said side opening is blocked, said first resilient member urging said plunger towards an annular ram which urges said lip radially towards the push rod by wedging it.
In that type of pump the radial force exerted on said lip of the plunger is not accurately controlled. This can eventually lead to deformation of the lip as the result of creep, to jamming of the lip into the side opening of the push rod, and possibly to tearing of the lip.